For me, the definition of a good exchange is those that have considered and prioritize the needs and satisfaction of their users. When it comes to security or any transaction the user can say that is safe to place and trust for their assets.
You do not just simply enter your assets into an exchange just because it is recommended to you. It is still a good idea to do some research yourself so that you can be more aware of its advantages and disadvantages.
Especially if you plan to trade. It is best to do a background check first so that no matter what transaction you make, everything will be fine.
Me? i am currently in kucoin. Because this is what i prefer my assets and surely get good security, also where my questions can be answered immediately once I encountered a problem since it has 24/7 service. I actually keep trading and traded some coins here like
BTC,
XRP and
ETH.
But remember, as a trader, it is still up to you how you will handle your cryptocurrencies, as long as you are aware of the market trend and carefully study the exchange you want to enter. Google and the official sites of each exchange are just there, you can visit it if you really want to be its user.